The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
Not applicable.
(1) Field of the Invention
The present invention relates generally to electrical hull penetrators and, more specifically, to electrical hull penetrators that allow passage of analog or digital signals across a rigid boundary (i.e., a submarine hull) without a physical hole being made in the boundary.
(2) Description of the Prior Art
Vessels operated in water typically require the use of devices, such as sensors or processors, that are located on the external side of the associated hull and immersed in water. The information gathered by these devices needs to be transferred to equipment located internal to the vessel and to do so commonly requires a hull penetrator, that is, a device that causes openings to be forced through the hull, such as a Submarine Electrical Hull Penetrator used for a pressure hull of a submarine.
Submarine Electrical Hull Penetrators (EHPs) are costly. Every hole cut into the pressure hull requires sub-safe approval at multiple levels of responsibility and custody. Further, EHPs require a large amount of supporting documentation and testing over the life-cycle of an installation, such as a submarine. EHPs add weight to the submarine and weaken the hull. The highcost and typical snail-slow approval process for adding a new EHP prevents short-term, special purpose, installations for experimental gear, or special deployments. If one could take the penetration (i.e., the hole) out of the EHP, tremendous cost advantage would be reaped.
A Penetration-less Electrical Hull Penetrator (PEHP) would remove the current focus on submarine survival and allow a restoration of focus on the functionality and survival of the wet end equipment, that is, equipment designed to withstand continuous immersion in water. A PEHP would significantly lower the cost and would greatly accelerate the approval and installation of wet end equipment. Further, a PEHP would greatly decouple wet end equipment requirements from the major sub-safe considerations (i.e., hull breach).
Systems that provide the transmission of information through solid boundaries are known and some of which are disclosed in U.S. Pat. Nos. 4,932,006, 5,437,058 and 5,982,297. U.S. Pat. No. 4,932,006 discloses a method for transmitting a signal through a wall/hull by passing a current therethrough and measuring magnetic field variations generated thereby. U.S. Pat. No. 5,437,058 discloses a wireless shipboard data coupler, wherein a 1 MHz current is injected into the hull and flows along its surface and wraps around walls where it is detected. The data is modulated prior to being xe2x80x9cinjectedxe2x80x9d into the hull. U.S. Pat. No. 5,982,297 discloses an ultrasonic data communication system for transforming data through a medium which can be metal. Data is modulated, amplified and transmitted through medium as an ultrasonic signal where it is detected/demodulated. It is desired to provide a system particularly suited for a submarine and for the transmission of electrical signals through a solid boundary, such as a hull, without the need of using an applied current or without being limited to the use of ultrasonic signals; that is, without suffering the corresponding transmission loss by using an ultrasonic frequency in the region of 20 to 108 KHz.
The submarine hull is fabricated with thick steel and there are two ways for a signal to penetrate this steel; i.e., magnetically or acoustically. The magnetic option is limited by at least three factors: low induction efficiency, electromagnetic signature (when surfaced) and degaussing considerations. All of these factors compete against using magnetic coupling. It is desired to implement acoustic means for a PEHP. More particularly, it is desired that acoustic means be provided for passing electrical signals through a hull without the need of holes being placed in the hull itself.
Therefore, it is an object of the present invention to provide a system for acoustically passing electrical signals through a solid rigid boundary, such as a hull of a vessel operated in water, and without creating holes in the boundary.
It is another object of the present invention to provide a hole free data transmission path between the external (immersed in water) and internal (free of water) surfaces of a hull.
It is still another object of the present invention to provide a system comprised of conventionally wet-end equipment for acoustically passing electrical signals through a hull.
Accordingly, the current invention provides a system for acoustically passing electrical signals through a solid rigid boundary comprised of metal and having first and second opposite surfaces being free of openings. The system comprises one or more first buffers for receiving electrical signals being transmitted from a first source and one or more first modulators operatively and respectively connected to the one or more first buffers for modulating and combining the received signals with a carrier signal and providing a representative modulated output therefrom. The system further comprises one or more first transmitting transducers arranged in contact with the first surface of the solid rigid boundary and operatively and respectively connected to the modulated outputs of the one or more first modulators and developing a first acoustic output signal representative thereof. The system further comprises one or more first receiving transducers arranged in contact with the second surface of the solid rigid boundary and in alignment with the first transmitting transducers on the first surface and operatively connected to receive the acoustic output signal of respective transmitting transducers and developing representative outputs thereof. The system further comprises one or more demodulators operatively and respectively connected to receive the representative output of respective one or more first receiving transducers and separating the carrier signal therefrom leaving a first unmodulated electrical signal. The system still further comprises one or more second buffers operatively and respectively connected to receive respective first unmodulated electrical signals of the one or more demodulators and developing representative signals for being transmitted to a second source.